There are a lot of pairs of terms in psychology that sound as if they refer to the same thing, and can therefore be used interchangeably, when in fact they refer to different concepts that are distinct in important ways. As Emory University professor Scott Lilienfeld and his colleagues point out in their new open-access paper in Frontiers in Education, even experienced psychologists and science communicators sometimes confuse these pairs of terms, which inevitably impedes their understanding of the underlying concepts.

Their new paper outlines 50 “frequently confused term pairs in psychology” from across different fields of psychology and related subjects. “Our list … should hopefully be a modest contribution toward enhancing psychological literacy and critical thinking in psychology more broadly,” they write.

Below we’ve highlighted 10 of the pairs of psychology terms that Lilienfeld and his co-authors believe you might be getting confused (check the full paper for the other 40):

“Negative Reinforcement” versus “Punishment”
A few years ago ABC news reported “British Soccer Players Get Negative Reinforcement“. The story was about the players who’d played badly being made to drive around in an old, uncool car. But this wasn’t negative reinforcement, it was a punishment: an unpleasant experience intended to deter future bad play. Negative reinforcement, by contrast, is a reward in the form of the removal of a previously unpleasant stimulus or experience, thus increasing the likelihood of the behaviour that preceded it.

“Envy” versus “Jealousy”
A lot of us use these terms interchangeably not realising that envy is specifically about the dynamics between two people whereas jealousy involves three or more. A leading researcher in this area is psychologist Richard Smith. He explains at Psychology Today: “Envy occurs when we lack a desired attribute enjoyed by another” whereas “Jealousy occurs when something we already possess (usually a special relationship) is threatened by a third person”.

“Antisocial” versus “Asocial”
Both sound very similar if we’re not paying attention. The clue of course is that the prefix “anti” means against, where as the prefix “a” means without. In psychology, anti-social is often used in the context of antisocial personality disorder, which describes a person who behaves against others, engaging “in reckless, irresponsible, and at times illegal behaviours” (to quote Lilenfeld et al). By contrast, an asocial person is “shy or disinterested in interpersonal contact”. Lilienfeld and his coauthors give the example of a Huffington Post article that conflated this distinction, stating: “the idea that introverts are antisocial or don’t want the company of others is completely false”.

“Obsession” versus “Compulsion”
Easy to confuse, but in terms of Obsessive Compulsive Disorder, obsessions are anxiety-generating repetitive thoughts, urges or images (e.g. “I feel dirty”, “I’ve been contaminated”), whereas compulsions are the behaviours or mental acts that the person performs to try to reduce their anxiety (e.g. hand washing).

“Psychopathy” vs. “Sociopathy”
You might have heard an unpleasant character described as a sociopath and wondered if that’s the same or different from a psychopath. At least in the context of clinical and forensic psychology, Lilienfeld et al explain that a psychopathic personality is defined by a specific mix of features including superficial charm and callousness. Sociopathy on the other hand is not a formal or technical term, and it’s used to mean different things by different people, for example as a synonym for psychopath or to describe someone with a long history of criminal behaviour.

“Serial killer” versus “Mass murderer”
While we’re on the subject of criminal characters, Lilienfeld et al also highlight an important distinction in forensic psychology between types of murderer: Serial killers (e.g. Peter Sutcliffe AKA the Yorkshire Ripper) kill “multiple people in a string of incidents that are separated by ‘cooling off’ periods,” while mass murderers (e.g. Thomas Hamilton, the perpetrator of the mass shooting at a Dunblane school) massacre “a large number of people in a single incident”. For completeness, Lilienfeld’s team add that spree killers form another group: like serial killers, they kill multiple people in separate incidents, but unlike serial killers their “homicidal episodes are not separated by clear-cut cooling-off periods”.

“Mediator” versus “Moderator”
From types of killer to statistical nuance. As Lilienfeld at al explain, “A mediator is a variable, C, that intervenes between two correlated variables A and B, and that accounts at least in part … or entirely … for their statistical association.” Mediators speak to the why of an association. For example, a 2011 study found that listening to prosocial songs like Michael Jackson’s Heal the World was associated with lower aggression and that this seemed to be partly mediated by the effect of the song on listeners’ mood rather than on their thoughts. A moderator, by contrast, “is a variable, C, that statistically affects the direction, magnitude, or both, of the relation between variables A and B”. Lilienfeld et al give the example of the association between negative life events and severity of illness, which is stronger for uncontrollable events (e.g. death of a spouse) than more controllable ones (e.g. divorce). “Moderators tend to address ‘when’, ‘for whom’, and ‘under which’ questions,” Lilienfeld explain.

“Prevalence” versus “Incidence”
What proportion of the population have a mental health diagnosis? The answer would tell you the prevalence of mental health problems. How many people are newly diagnosed with mental health problems in a given year (or other time period)? The answer to that question would tell you the incidence. “More technically,” explain Lilienfeld et al, “prevalence equals incidence multiplied by duration.”

“Coma” versus “Persistent Vegetative State”
Lilienfeld’s team place this one in their miscellaneous category. Coma and persistent vegetative state (PVS) are closely related, they explain, “but should be distinguished”. I covered misconceptions about these states and other disorders of consciousness at length in my 2014 book Great Myths of the Brain. While coma and PVS are bothcaused by brain damage and are associated with a lack of conscious awareness, there are important differences in the two states: Coma patients’ brains show no sign of a sleep wake cycle because of damage to the reticular system; in contrast PVS patients’ brains have an intact reticular system and show signs of a sleep wake cycle. Indeed, a PVS patient will usually have their eyes open during the wake part of the cycle (which can be confusing for loved ones and give false hope) and their eyes closed during the sleep phase. Also, coma patients are totally unresponsive whereas PVS patients often move and make sounds, and they may respond to noises and momentarily track moving targets with their eyes. Coma patients who survive but don’t wake up may progress to a PVS. If it is believed that a PVS patient has some rudimentary awareness, their diagnosis is changed to “minimally conscious state”.

“Relapse” versus “Recurrence”
To grasp the distinction between relapse and recurrence, it helps also to realise the difference between “remission” from a psychological disorder (a full improvement that has lasted at least four months after treatment) and “recovery” (full improvement that’s lasted more than a year). According to Lilienfeld and his colleagues, relapse is when a condition returns after the start of remission but before recovery. Recurrence, by contrast, is when the condition returns after recovery.

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Remember to check the full paper for 40 more psychological term pairs that you might be getting confused. Also well worth reading, two years ago Lilienfeld and co produced a complementary paper listing 50 widely used psychological and psychiatric terms that should probably be avoided.

Good stuff. I often get frustrated at professionals and practitioners casually using terms interchangeably. God knows what it must be like to be a patient hearing multiple erroneous terms for something that’s actually quite simple.